Polymeric bags and method of forming polymeric bags

ABSTRACT

The present invention relates to improvements for the manufacturing of a wave-cut bag of polymeric film, more specifically a wave-cut bag with a body having improved shock, tear and puncture resistance. The polymeric film has an embossed pattern of a plurality of embossed regions that are comprised of a plurality of parallel, linear embosses. Further disclosed is a process for intermittently applying the embossed pattern to a collapsed tube of a blown film extrusion process. The collapsed tube with the intermittently applied embossed pattern is particularly well suited for constructing wave-cut trash bags with the embossed pattern applied to a central body of the wave-cut bags.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of pending U.S. applicationSer. No. 15/139,480, filed Apr. 27, 2016, which is acontinuation-in-part of U.S. application Ser. No. 14/659,785, filed Mar.17, 2015, now U.S. Pat. No. 9,487,334. This application is also acontinuation-in-part of pending U.S. application Ser. No. 14/645,533,filed Mar. 12, 2015. All three of the aforementioned applications arehereby incorporated by reference into this disclosure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to improvements in bags made frompolymeric film and processes for manufacturing polymeric film bags.

2. Description of the Related Art

Polymeric films are used in a variety of applications. For example,polymeric films are used in sheet form for applications such as dropcloths, vapor barriers, and protective covers. Polymeric films can alsobe converted into plastic bags, which may be used in a myriad ofapplications. The present invention is particularly useful to trash bagsconstructed from polymeric film.

Polymeric bags are ubiquitous in modern society and are available incountless combinations of varying capacities, thicknesses, dimensions,and colors. The bags are available for numerous applications includingtypical consumer applications such as long-term storage, food storage,and trash collection. Like many other consumer products, increaseddemand and new technology have driven innovations in polymeric bagsimproving the utility and performance of such bags. The presentinvention is an innovation of particular relevance to polymeric bagsused for trash collection and more particular for larger bags used forthe collection of larger debris, such as yard debris.

Polymeric bags are manufactured from polymeric film produced using oneof several manufacturing techniques well-known in the art. The two mostcommon methods for manufacture of polymeric films are blown-filmextrusion and cast-film extrusion. In blown-film extrusion, theresulting film is tubular while cast-film extrusion produces a generallyplanar film. The present invention is generally applicable to drawstringtrash bags manufactured from a blown-film extrusion process resulting intubular film stock. Manufacturing methods for the production of bagsfrom a collapsed tube of material are shown in numerous prior artreferences including, but not limited to, U.S. Pat. Nos. 3,196,757 and4,624,654, which are hereby incorporated by reference.

In blown film extrusion, polymeric resin is fed into an extruder wherean extrusion screw pushes the resin through the extruder. The extrusionscrew compresses the resin, heating the resin into a molten state underhigh pressure. The molten, pressurized resin is fed through a blown filmextrusion die having an annular opening. As the molten material ispushed into and through the extrusion die, a polymeric film tube emergesfrom the outlet of the extrusion die.

The polymeric film tube is blown or expanded to a larger diameter byproviding a volume of air within the interior of the polymeric filmtube. The combination of the volume of air and the polymeric film tubeis commonly referred to as a bubble between the extrusion die and a setof nip rollers. As the polymeric film tube cools travelling upwardtoward the nip rollers, the polymeric film tube solidifies from a moltenstate to a solid state after it expands to its final diameter andthickness. Once the polymeric film tube is completely solidified, itpasses through the set of nip rollers and is collapsed into a collapsedpolymeric tube, also referred to as a collapsed bubble.

One common method of manufacturing trash bags involves segregating thecollapsed polymeric tube into individual trash bags by forming sealswhich extend transversely across the entire width of the tube.Typically, a line of perforations is formed immediately adjacent andparallel to each seal to facilitate separation of the trash bags onefrom another. After the trash bags are sealed and perforated, the trashbags can be twice-folded axially into a fractional width configuration.

It is also known to provide wave-cut trash bags. A wave-cut trash baghas a wave or lobe-shaped configuration at its open end. This providestwo or more lobes, which can be used to tie the trash bag in a closedconfiguration after it is filled with refuse.

Wave-cut trash bags can be manufactured by providing closely spaced,parallel transversely extending seals at predetermined intervals alongthe collapsed polymeric tube. A transversely extending line ofperforations is provided between the closely spaced, parallel seals. Thecollapsed polymeric tube is then separated longitudinally along a waveor lobe-shaped line located equidistant between the edges of the tube.

The lobe-shaped features, or lobes, of a wave-cut trash bags, which mayalso be referred to as tie-flaps, provide a convenient user feature totie and close the opening of the bag. The lobes are grasped and knottedto seal the bag opening. Representatives of wave-cut or “tie bags” canbe found in the following prior art of U.S. Pat. Nos. 4,890,736,5,041,317, 5,246,110, 5,683,340, 5,611,627, 5,709,641, and 6,565,794,which are hereby incorporated by reference into this disclosure.

In a further publication, U.S. Pat. Appl. Pub. 2008/0292222A1 disclosesa bag having at least two “tie flaps” with gripping features embossed onat least one surface of the tie flaps. It is further disclosed that thebag may be formed from a tube of polymeric material. However, thepublication further discloses that the gripping feature is formed in alinear fashion along a length of a blown film bubble that is then slitlengthwise in a wave pattern. The bubble is then formed into bags afterbeing collapsed with a collapsed edge forming a bottom of the bag.

It has been determined, however, that the lobes of prior art wave-cutbags are often difficult to grasp and manipulate, especially if thelobes are contaminated with slippery trash contamination such as oil orgrease or moist organic contaminants. Furthermore, wave-cut bags areoften manufactured with thicker film than other types of trash bagssince they often are intended for use with larger and heavier debris,such as yard debris and debris from home improvement projects. Thesethicker films used on larger wave-cut bags can be as thick as 3 mils andmake it challenging for a user to manipulate the lobes of a wave-cut baginto a knot. Hence, it would be desirable to provide a wave-cut bag thathas easier to grasp lobes that are also thinner than the rest of thebag. The present invention represents a novel solution to address thisneed.

It has also been determined that for certain thicknesses of wave-cuttrash bags it may be desirable to provide a bag with thicker lobesrelative to thinner a central body of the bag. Thicker lobes may providea perception of strength to a user when handling the bag and provide abag that forms a more robust closure. The thinner body of the bag allowsa manufacturer to provide thicker lobes that are desired by consumerswhile also using less raw material than would otherwise be required toform a bag with a uniform thickness having the same thickness the areaof the bag's lobes.

Additional problems are understood to be inherent with the use ofpolymeric films in trash bags. For instance, the use of polymeric filmpresents technical challenges since polymeric film is inherently softand flexible. Specifically, all polymeric films are susceptible topuncture and tear propagation. In some instances, it may be possible toincrease the thickness of the film or select better polymers to enhancethe physical properties of the film. However, these measures increaseboth the weight and cost of the polymeric film and may not bepracticable. In light of the technical challenges of polymeric film,techniques and solutions have been developed to address the need forimproved shock absorption to reduce the likelihood of puncture. Forexample, it is known to impart stretched areas into polymeric films as ameans of inducing shock absorption properties into the film.

U.S. Pat. No. 5,205,650, issued to Rasmussen and entitled Tubular Bagwith Shock Absorber Band Tube for Making Such Bag, and Method for itsProduction, discloses using polymeric film material with stretchablezones wherein the film material has been stretched in a particulardirection with adjacent un-stretched zones that extend in substantiallythe same direction. The combination of the stretched zones and adjacentun-stretched zones provides a shock absorber band intended to absorbenergy when the bag is dropped. Specifically, when a bag is dropped ormoved, the contents inside the bag exert additional forces that wouldotherwise puncture or penetrate the polymeric film. However, the shockabsorber bands absorb some of the energy and may prevent puncture of thefilm.

Another example of a polymeric film material designed to resist punctureis disclosed in U.S. Pat. No. 5,518,801, issued to Chappell and entitledWeb Materials Exhibiting Elastic-Like Behavior. Chappell, in theaforementioned patent and other related patents, discloses using aplurality of ribs to provide stretchable areas in the film much likeRasmussen. Chappell also discloses methods of manufacturing suchpolymeric film with such ribs.

Another example of shock absorption to prevent puncture is disclosed inU.S. Pat. No. 5,650,214 issued to Anderson and entitled Web MaterialsExhibiting Elastic-Like Behavior and Soft Cloth-Like Texture. Andersondiscloses using a plurality of embossed ribs defining diamond-shapedareas with a network of unembossed material between the diamond-shapedareas. Thus, the unembossed area comprises a network of straight, linearunembossed material extending in two perpendicular directions.

The foregoing disclosures specifically address the desire to increasethe shock absorption of polymeric film to reduce the likelihood ofpunctures occurring in the film. However, none of the foregoingdisclosures address the problem of reducing tear propagation in thepolymeric film of a bag.

Previously known solutions to limiting tear propagation are based on twoprimary concepts. First, longer and more tortuous tear paths consumemore energy as the tear propagates and can help in limiting the impactof the tear in a bag or polymeric film. Second, many polymeric films,particularly polymeric films made using a blown-film extrusion process,have different physical properties along different axes of the film. Inparticular, blown films are known to have higher tear strength in thecross-direction versus the corresponding tear strength in the machinedirection. Certain prior art solutions take advantage of thedifferential properties of polymeric films by redirecting tears into adifferent direction. This redirecting of tears can offer greaterresistance to a tear propagating. For example, some solutions redirect atear propagating in the weaker machine direction of blown film into thestronger cross-direction.

One solution for reducing tear propagation is based on the idea thatlonger, tortuous tear paths are preferable and is described in U.S. Pat.No. 6,824,856, issued to Jones and entitled Protective Packaging Sheet.Jones discloses materials suitable for packaging heavy loads byproviding an embossed packaging sheet with improved mechanicalproperties. Specifically, a protective packaging sheet is disclosedwhere surfaces of the sheet material are provided with protuberancesdisposed therein with gaps between protuberances. The protuberances arearranged such that straight lines necessarily intersect one or more ofthe protuberances. The resulting protective packaging sheet providesmechanical properties where tears propagating across the polymeric sheetare subject to a tortuous path. The tortuous path is longer, and morecomplex, than a straight-line tear, and a tear propagating along such apath would require markedly more energy for continued propagation acrossthe film compared to a tear along a similar non-tortuous path in thesame direction. Thus, due to the increased energy required for tearpropagation, the tortuous path ultimately reduces the impact of anytears that do propagate across the film.

Another example of a tear resistant plastic film is disclosed in U.S.Pat. No. 8,357,440, issued to Hall and entitled Apparatus and Method forEnhanced Tear Resistance Plastic Sheets. Hall discloses an alternativetortuous path solution and further relies on the fact discussed abovethat certain polymer films, particularly polymeric films made in ablown-film extrusion process, are known to have a stronger resistance totear in the cross direction when compared to the machine direction.

Hall discloses a solution that contemplates using preferably shapedembosses, particularly convex shaped embosses with a curved outerboundary, to provide maximum resistance to tear propagation. In mostpolymeric films, a tear will have a tendency to propagate along the pathof least resistance or in the machine direction. Hall contemplatesredirecting propagating tears in a tortuous path with the additionalintent of redirecting the machine direction tears along the curved edgesof the embossed regions and into a cross direction orientation. Theredirected tears in the cross direction will be subject to additionalresistance and, preferably, will propagate to a lesser degree than atear propagating in the machine direction in an unembossed film.

U.S. Pat. No. 9,290,303 to Brad A. Cobler (the Cobler patent) with afiling date of Oct. 24, 2013, herein incorporated by reference into thisdisclosure, discloses use of an embossing pattern on polymeric film thatbalances both properties of shock absorption and tortuous tear paths inthe cross direction, into a single, practicable polymeric film. Thepatent discloses that the embossing pattern comprises a plurality ofembossed regions comprised of a plurality of parallel, linear embosses.The plurality of embossed regions is arranged so that a straight linecannot traverse the polymeric film without intersection at least one ofthe plurality of embossed regions.

It would be desirable to provide the polymeric film of the body ofwave-cut trash bags, or the body of trash bags in general, with theembossing pattern of the Cobler patent. A bag with this pattern wouldprovide a trash bag with improved shock absorption and resistance totear propagation in comparison to the state of the art wave-cut trashbags. It would also be desirable to provide a wave-cut bag with theCobler embossing pattern only in the body of the bag and not in thebottom area of the bag or in the lobes of the wave-cut opening. Theemboss pattern defined only in the body of the bag would provide theabove-discussed advantages without the embossing pattern interferingwith the tying of the bag with the lobes or interfering with the bottomseal of the bag. The present invention addresses these additionalobjectives.

SUMMARY OF THE PRESENT INVENTION

In at least one embodiment of the present invention, a bag of polymericfilm may be formed. To form the polymeric bag, a collapsed tube ofpolymeric film may be formed with a machine direction. The collapsedtube may be formed from a blown film extrusion process. Once thecollapsed tube is formed, a pair of intermeshing rollers mayintermittently engage the collapsed tube to form a plurality of embossedsections and unembossed sections in the collapsed tube. Each of theembossed sections may comprise a plurality of embossed regions and eachof the embossed regions may be separated from adjacent embossed regionsby an unembossed arrangement.

Once the collapsed tube is embossed, a bag converting operation may formthe collapsed tube into a plurality of bags. Each one of the pluralityof bags may have at least a fraction of one of the plurality of embossedsections. Each of the embossed sections may extend across the entirewidth of the collapsed tube. The bag converting operation may furthercomprise forming sets of closely spaced, parallel seals extendingtransversely across the entire width of the collapsed tube. Each set ofclosely spaced parallel seals may be at equally spaced intervals fromeach other. The bag converting operation may also form perforation linesextending transversely across the entire width of the collapsed tubewith a perforation line located between each set of closely spaced,parallel seals. A plurality of wave-shaped perforations may also beformed in the collapsed tube. A location of each wave-shaped perforationmay be equidistant from adjacent perforation lines. Each wave-shapedperforation may be centered within one of the plurality of incrementallystretched sections.

The converting operation may further comprise a timing operation. Thetiming operation may detect the location of each perforation line andgenerate a timing signal. The location of each wave-shaped perforationand embossed section may be based upon the timing signal. The timingoperation may be a standalone operation or may be integrated into thebag converting operation. The timing signal may trigger the intermeshingrollers to engage and disengage the collapsed tube twice to form twoembossed sections for each timing signal generated.

The pair of intermeshing rollers of the embossing process maycounter-rotate in relation to each other so that the collapsed tube isfed through the pair of intermeshing rollers. Each roller may have arotational axis and the two axes of the rollers may be parallel witheach other. The axes of each of the pair of intermeshing rollers mayalso be perpendicular to the machine direction of the collapsed tube.The pair of intermeshing rollers may comprise a first roller and asecond roller. The first roller may include a plurality of groovesperpendicular to the axis of the first roller. The plurality of grooveson the first roller may intermesh with an embossing pattern on thesecond roller. Each intermeshing roller may rotate in a direction thatthe collapsed bubble is moving so that the bubble is drawn through thepair of intermeshing rollers. A pair of post-embossing rollersdownstream from the pair of intermeshing rollers and a pair ofpre-embossing rollers upstream of the intermeshing rollers may beprovided to control the tension in the collapsed tube when it passesthrough the intermeshing rollers.

In at least certain embodiments, the embossing pattern may comprise aplurality of embossment regions defined in the second roller and eachembossment region may comprise a plurality of embossment ridges. Each ofthe plurality of embossment ridges may be linear and parallel to eachother. Each embossment region may be defined by a continuous embossmentboundary. The embossment boundary may be generally flat and comprise atleast a plurality of first segments and a plurality of second segments.The plurality of first segments may extend in a first direction and theplurality of second segments may extend in a second direction. The firstand second directions may be distinct from each other. The embossmentboundary may further comprise a plurality of third segments extending ina third direction with the third direction distinct from the first andsecond directions. The embossment boundary may also be devoid ofembossment ridges.

In a further embodiment of the present invention, a bag is formed form acollapsed tube of polymeric film. The bag may comprise a first panel anda second panel. The first panel and the second panel may be joined alonga first side edge, a second side edge, and a bottom edge by a bottomseal. The bottom seal may extend from the first side edge to the secondside edge. The first side edge may be formed from a first edge of thecollapsed tube and the second side edge may be formed from a second edgeof the collapsed tube. The first panel may have a first top edgeopposite the bottom edge and the second panel may have a second top edgeopposite the bottom edge. The first top edge and second top edge maydefine an opening of the bag. A distal end of both the top edge andsecond top edge may have a wave-shaped profile and the wave-shapedprofile may define a plurality of lobes. In at least one embodiment, anembossed section may be defined only below the plurality of lobes andthe embossed section may comprise a plurality of embossed regions. Eachof the embossed regions may be separated from adjacent embossed regionsby an unembossed arrangement. The embossed section may extend from thefirst side edge to the second side edge.

In an additional embodiment of the present invention, a bag is formedform a collapsed tube of polymeric film. The bag may comprise a firstpanel and a second panel. The first panel and the second panel may bejoined along a first side edge, a second side edge, and a bottom sealproximate to a bottom edge. The first side edge may be formed from afirst edge of the collapsed tube and the second side edge may be formedfrom a second edge of the collapsed tube. The first panel may have afirst top edge opposite the bottom edge and the second panel may have asecond top edge opposite the bottom edge. The first top edge and secondtop edge may define an opening of the bag. A distal end of both the topedge and second top edge may have a wave-shaped profile comprising aplurality of crests and troughs.

The bag of the embodiment may further include an upper embossmentboundary below the plurality of troughs of the wave-shaped profile. Theupper embossment boundary may extend from the first side edge to thesecond side edge. A lower embossment boundary may be defined below theupper embossment boundary and above the bottom seal. The lowerembossment boundary may extend from the first side edge to the secondside edge. An embossed section may extend between the first side edgeand the second side edge. The embossed section may also extend betweenthe upper embossment boundary and the lower embossment boundary. Theembossed section of the bag may comprise a plurality of embossed regionsof embossments. Each embossed region may be separated from adjacentembossed regions by an unembossed arrangement. A first unembossedsection may extend from the upper embossment boundary to the pluralityof crests and from the first side edge to the second side edge. Thefirst unembossed section may have a generally flat surface and be devoidof embossments. A second unembossed section may extend from the lowerembossment boundary to the bottom edge and from the first side edge tothe second side edge. The second unembossed section may have a generallyflat surface and be devoid of embossments.

In at least certain embodiments, the continuous unembossed arrangementmay comprise at least a plurality of first segments and a plurality ofsecond segments. The plurality of first segments may extend in a firstdirection and the plurality of second segments may extend in a seconddirection. The first and second directions may be distinct from eachother. The first and second embossment boundaries may be generallylinear and parallel to the bottom seal. A machine direction of thecollapsed tube may extend in a direction generally perpendicular to thebottom seal. The bottom seal may be generally perpendicular to the firstside edge and the second side edge. Each of the embossed regions maycomprise linear ribs and each linear rib may be generally perpendicularto the first side edge and the second side edge. A first transition zonemay be between the embossed section and the first unembossed section.The first transition zone may comprise a plurality of linearembossments. The plurality of linear embossments may have taperingheights with a height of the linear embossments decreasing as the linearembossments extend towards the first unembossed section. The embossedsection may further be formed from a pair of intermeshing rollers.

BRIEF DESCRIPTION OF THE RELATED DRAWINGS

A full and complete understanding of the present invention may beobtained by reference to the detailed description of the presentinvention and certain embodiments when viewed with reference to theaccompanying drawings. The drawings can be briefly described as follows.

FIG. 1 depicts a perspective view of a first embodiment of the presentinvention.

FIG. 2a depicts a partial perspective view of the first embodiment ofthe present invention.

FIG. 2b depicts a partial perspective view of an alternate secondembodiment of the present invention.

FIG. 3a depicts a perspective view of an incremental stretchingoperation of the first and second embodiments.

FIG. 3b depicts a secondary perspective view of the incrementalstretching operation of the first and second embodiments.

FIG. 4a depicts a perspective view of an incremental stretchingoperation of a third embodiment of the present invention.

FIG. 4b depicts a perspective view of an incremental stretchingoperation of a fourth embodiment of the present invention.

FIG. 5 depicts a front view of a fifth embodiment of the presentinvention.

FIG. 6 depicts another front view of the fifth embodiment of the presentinvention.

FIG. 7 depicts a front view of a sixth embodiment of the presentinvention.

FIG. 8 depicts another front view of the sixth embodiment of the presentinvention.

FIG. 9 depicts a top planar view of an intermeshing roller of a seventhembodiment of the present invention.

FIG. 10 depicts a front view of a trash bag of the seventh embodiment ofthe present invention.

FIG. 11 depicts a side view of the gradual transition from an un-ribbedto a ribbed polymeric film due to an incremental stretching operation.

FIG. 12 depicts a perspective view of an eighth embodiment of thepresent invention.

FIG. 13 depicts a partial perspective view of the eighth embodiment ofthe present invention.

FIG. 14 depicts a top view of an embossing pattern of the eighthembodiment.

FIG. 15a depicts a perspective view of an incremental stretchingoperation of the eighth embodiment.

FIG. 15b depicts a second perspective view of the incremental stretchingoperation of the eighth embodiment.

FIG. 16 depicts a perspective planar or flattened view of a section ofan embossing roller of the eighth embodiment.

FIG. 17 depicts a front view of a ninth embodiment of the presentinvention.

FIG. 18 depicts a front view of a tenth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure illustrates several embodiments of the presentinvention. It is not intended to provide an illustration or encompassall embodiments contemplated by the present invention. In view of thedisclosure of the present invention contained herein, a person havingordinary skill in the art will recognize that innumerable modificationsand insubstantial changes may be incorporated or otherwise includedwithin the present invention without diverging from the spirit of theinvention. Therefore, it is understood that the present invention is notlimited to those embodiments disclosed herein. The appended claims areintended to more fully and accurately encompass the invention to thefullest extent possible, but it is fully appreciated that certainlimitations on the use of particular terms are not intended toconclusively limit the scope of protection.

Referring initially to FIGS. 1 and 2, a process for forming wave-cuttrash bags with incrementally stretched tie flaps or lobes is shown. Thetrash bags may be formed by a blown film extrusion process. The blownfilm extrusion process begins by molten polymeric resin being extrudedthrough an annular die of an extruder, or extrusion operation 102 toform a bubble or tube of molten polymeric film 104. The direction thatthe film is extruded out of the die is commonly referred to as themachine direction (MD). The direction of extrusion may also be referredto as the lengthwise direction of the bubble or polymeric film tube 104.Hence, the length of the polymeric tube 104 extends parallel with themachine direction. The direction transverse to the machine direction iscommonly referred to as the cross direction (CD). The blown filmextrusion process is well known in the art and is further explained inU.S. Pat. No. 7,753,666, which is hereby incorporated by reference.

The polymeric resin used in the blown film extrusion process may vary.However, for forming polymeric bags, a polyethylene resin is commonlyused. In the current state of the art for polymeric bags, a blend ofvarious polyethylene polymers may be used. A polymer blend can havelinear low-density polyethylene (LLDPE) as the primary component, butother polymers may be utilized including, but not limited to, otherpolyethylene resins such as high-density polyethylene (HDPE) orlow-density polyethylene (LDPE). Typically, the primary component of thepolymer blend, such as linear low-density polyethylene (LLDPE), willcomprise at least 75% of the polymer blend. The remaining portion of thepolymer blend may include additives including, but not limited to,coloring additives, anti-blocking agents, and/or odor control additives.The film utilized to form polymeric bags may also comprise multiplelayers of blown film resin. The resultant multi-layer film may be formedby coextrusion, a lamination process, or other methods of forming amulti-layer film known in the art. In each layer, one or more of theabove-discussed polymers may be used.

As shown in FIG. 1, once the bubble 104, or polymeric tube, of moltenfilm solidifies, the bubble 104 is collapsed by a pair of nip rollers108, which results in a collapsed tube 110. The collapsed tube 110includes two opposing interconnected surfaces of film extendingcontinuously in a lengthwise direction. This continuously extendingsurface of film may be referred to as a web. The nip rollers 108 arecommonly elevated above the extruder 106 a considerable distance, sincethe molten bubble 104 is air-cooled and requires a relatively largevertical distance to cool and solidify before the bubble 104 iscollapsed.

As shown in FIG. 2a , once collapsed, the collapsed tube 110 has a firstedge 112 and second edge 114 defined in the opposing edges of thecollapsed tube 110 extending the length of the collapsed tube 110. Thedistance from the first edge 112 to the second edge 114 of the collapsedtube 110 can define a width of the collapsed bubble. Once the collapsedtube 110 returns from the cooling tower (not shown), the collapsed tube110 can feed directly into an incremental stretching operation 120;hence the incremental stretching can be performed as an in-line process,synchronously, with the blown film extrusion. As shown in FIG. 1 andmore clearly in FIG. 2a , the incremental stretching operation 120 canbe configured to only intermittently stretch the collapsed tube 110,leading to incrementally stretched partial lengths of the collapsed tube110.

As shown in FIGS. 3a-4b , the incremental stretching operation 120 caninclude a pair of intermeshing rollers 122 a, 122 b. The diameter andlength of each intermeshing roller 122 a, 122 b are equal in a preferredembodiment but may vary. As best shown in FIG. 3a , the collapsed tube110 can enter a nip 124 defined by the pair of intermeshing rollers 122a, 122 b. The rotational axes 128 a, 128 b of each roller 122 a, 122 bcan be parallel to each other and transverse to the machine direction(MD) of the collapsed tube 110. Each of the rollers 122 a, 122 b canhave a plurality of protruding ridges 126 parallel to the axis of eachroller 128 a, 128 b that extend around the entire circumference of eachroller 122 a, 122 b at a constant spacing. The protruding ridges 126 ofthe rollers 122 a, 122 b can be configured to intermesh like gears. Asthe collapsed tube 110 enters the nip of the intermeshing rollers 122 a,122 b, the film of the collapsed tube 110 is stretched based upon thedepth and spacing of the grooves 126.

As best shown in FIG. 3a , the film of the collapsed tube 110 isstretched by each groove of the plurality of protruding ridges 126 inthe machine direction, which results in a pattern of stretched andun-stretched lengths with each length extending along the width orcross-direction of the collapsed tube 110. Examined closely, thispattern of stretched and un-stretched lengths results in a pattern ofparallel thick ribs (un-stretched lengths) and thin ribs (stretchedlengths) extending in the cross-direction of the collapsed tube 110 foreach incrementally stretched section 116.

The preferred actual size and spacing of each of the plurality ofprotruding ridges 126 in relation to each of the rollers 122 a, 122 b issubstantially exaggerated for ease of illustration in the figures. Inone preferred embodiment, the spacing of the grooves can be 20 groovesper inch about the circumference of each roller 122 a, 122 b, with eachgroove leading to a matching thin rib/thick rib extending along thewidth of the collapsed tube 110. The spacing of the ribs in the filmafter stretching is greater than the groove spacing of the intermeshingrollers 122 a, 122 b, since the stretching causes the ribs to spreadaway from each other. The pattern of thick and thin ribs is representedby a pattern of parallel and adjacent lines in the figures.

Once again examining FIG. 3a and FIG. 3b , the incremental stretchingoperation 120 can be configured to only engage, and hence onlyincrementally stretch, the collapsed tube 110 intermittently. Thisintermittent engagement of the collapsed tube 110 leads to lengths ofun-stretched sections 118 and lengths of incrementally stretchedsections 116. As illustrated in FIG. 3b , the intermittent engagement ofthe collapsed tube 110 can be accomplished by the pair of intermeshingrollers 122 a, 122 b moving away from each other a certain distance Gallowing the collapsed tube 110 to move past the incremental stretchingoperation 120 without being stretched by the intermeshing rollers 122 a,122 b. The gap G, as shown in FIG. 3b , must be large enough to allowthe collapsed tube 110 to pass through the nip 124 without interferencefrom the intermeshing rollers 122 a, 122 b.

Shown in FIG. 4a is an alternative method of intermittentlyincrementally stretching the collapsed tube 110. Unlike the previousembodiment of the incremental stretching operation 120 shown in FIGS. 3aand 3b , the rotational axes 128 c, 128 d of the pair of intermeshingrollers 122 a, 122 b are mounted stationary in relation to each other.However, the protruding ridges 126 a, 126 b extend only partially aroundthe circumference of each roller 122 a, 122 b rather than about theentire circumference. The locations of the protruding ridges 126 a, 126b on each roller 122 a, 122 b are spaced appropriately so that theprotruding ridges 126 a, 126 b intermesh when the pair of rollers 122 a,122 b revolve. Thus, the collapsed tube 110 is incrementally stretchedonly when the protruding ridges 126 a, 126 b intermesh and engage thecollapsed tube 110. The geometry of each roller 122 a, 122 b can beconfigured so that the collapsed tube 110 is not in contact with eitherof the rollers 122 a, 122 b when not engaged with the protruding ridges126 a, 126 b. In the alternative, the diameter of each roller 122 a, 122b, can be configured such that the surface of one or more of the rollers122 a, 122 b is in contact with the collapsed tube 110 while theprotruding ridges 126 a, 126 b are not intermeshed. One or more of therollers 122 a, 122 b in contact with the collapsed tube 110, when theprotruding ridges 126 a, 126 b are not engaging the collapsed tube 110,may assist in maintaining the desired tension in the collapsed tube 110.

The rollers of FIG. 4a may rotate at a speed so that a tangential speedof each roller 122 a, 122 b matches a linear speed of the collapsed tube110 passing through the nip 124. In the alternative, the tangentialspeed of the rollers 122 a, 122 b may only match the speed of thecollapsed tube 110 when the collapsed tube 110 is engaged by theprotruding ridges 126 a, 126 b. When the protruding ridges 126 a, 126 bare not engaged, the rotational speed, and hence the tangential speed,of the pair of rollers 122 a, 122 b can be decreased. In this instance,the diameter of each roller 122 a, 122 b must be configured such thatthe collapsed tube 110 is not in contact with the rollers 122 a, 122 bwhen not engaged with the protruding ridges 126 a, 126 b, since thelinear speed of the collapsed tube 110 is typically constant. Decreasingthe speed of the rollers 122 a, 122 b when not engaged with the web hasthe advantage of allowing smaller diameter rollers than would berequired if the rollers rotated at a constant speed.

In one particular example, the incremental stretching operation 120 maybe configured such that each incrementally stretched section 116 of thecollapsed tube 110 is 15 inches in length after being stretched and eachun-stretched section 118 is 85 inches in length. For rollers that rotateat a constant speed, the intermeshing rollers can be configured tostretch the collapsed tube approximately 15 percent such that theprotruding ridges would extend about the circumference of each rollerapproximately 13 inches, stretching a length of 13 inches of thecollapsed tube 110, which results in a length of 15 inches after beingstretched. The remaining smooth circumference of 85 inches would then bedevoid of the protruding ridges, which results in a total circumferenceof approximately 98 inches and a diameter of approximately 31.2 inchesfor each roller 122 a, 122 b.

Unlike rollers that rotate at a constant speed, rollers 122 a, 122 bconfigured to run at an oscillating speed could have a smallercircumference and hence a smaller overall size. For instance, when notengaged, the rollers 122 a, 122 b could rotate with an averagetangential speed of 50 percent of the linear speed of the web. The speedof the rollers 122 a, 122 b would not step down instantly to 50 percent.Thus, the rollers 122 a, 122 b would first decelerate, then rotate at aspeed of less than 50 percent, and then accelerate prior to engaging thecollapsed tube 110 again. This arrangement would only require a smoothpartial circumference of one-half the previous smooth circumference ofapproximately 42.5 inches and a 13-inch partial circumference havingprotruding ridges 126 a, 126 b for a total circumference ofapproximately 55.5 inches and a diameter of approximately 17.7 inchesfor each roller 122 a, 122 b. It also foreseeable that the rollers couldrotate at an average tangential speed of much less than 50 percent whennot engaged with the collapsed tube, such as 25 percent.

Decreasing the diameter and hence the overall size of the rollers 122 a,122 b offers several advantages. First, the cost to produce the rollersis decreased with rollers of decreased size. In addition, with smallerrollers, the time to manufacture the rollers may also be reduced.Smaller rollers lead to lighter weight rollers, which can lead to amounting system for the rollers to be proportionally smaller and lessexpensive to construct. Lighter rollers may also lead to smaller, lessexpensive motors for driving the rollers. The use of smaller drivemotors may also lead to less energy consumption.

As shown in FIG. 4a , the axes 128 a, 128 b of the rollers 122 a, 122 bcan be located relative to the collapsed tube 110 so that the collapsedtube 110 passes equidistant from both rollers 122 a, 122 b. However, inan alternative embodiment shown in FIG. 4b , the collapsed tube 110 canbe located slightly further away from the bottom roller 122 b so thatprotruding ridges 126 may extend completely about the entirecircumference of the bottom roller 122 b. In such an embodiment, thecollapsed tube 110 passes over the lower protruding ridges 126 when notengaged by the upper protruding ridges 126 a. When the collapsed tube110 is engaged by the upper protruding ridges 126 a, the collapsed tube110 is pushed down into the lower protruding ridges 126 by the upperprotruding ridges 126 a.

In an alternative embodiment, the above-described incremental stretchingoperation 120 can be performed on a single layer web of polymeric film.For instance, the collapsed tube 110 may be slit along the first edge112 so that the tube is open along the first edge 112. The collapsedtube may then be spread out so that the two opposing layers of thecollapsed tube 110 lie in the same plane adjacent to each other. Thesingle layer web may then be intermittently incrementally stretched asdescribed above. Once the stretching is complete, the web may be foldedso that the two layers of the collapsed tube 110 once again oppose eachother. The two layers of film adjacent to the first edge 112 may then besealed together so that the collapsed tube 100 may still be used to formwave-cut trash bags. Performing the incremental stretching on one layerof film may prevent undesired binding of the two layers of film.

In another alternative embodiment, rather than the incrementalstretching operation 120 performed in-line and synchronously, asdescribed above, with the blown film extrusion 102, the incrementalstretching 120 can be performed off-line from the blown film extrusion.For instance, once the polymeric bubble 104 is collapsed by the niprollers 108, the collapsed tube 110 can be rolled onto a master roll.The master roll can then be placed at a lead end of the incrementalstretching operation 110 and the collapsed tube can be unrolled from themaster roll. The collapsed tube 110 can then be fed into the incrementalstretching operation 120.

Returning now to FIGS. 1 and 2, once the incremental stretching iscomplete, the collapsed tube 110 can enter a bag converter 140. The bagconverter 140 can form sets of closely spaced, parallel seals 142. Thesets of closely spaced parallel seals 142 can extend transversely to themachine direction and across the entire width of the collapsed tube 110.As shown in FIGS. 5 and 6, one seal of each set 142 can define a bottomseal 142 a for each bag 154 a. As shown in FIG. 2a , between each set ofthe closely spaced parallel seals 142, the bag converter 140 can formperforation lines 144. The perforation lines 144 can extend transverselyto the machine direction, the cross direction, and across the entirewidth of the collapsed tube 110. Each perforation line 144 can definethe bag bottom 144 a (shown in FIG. 5) and separation point of adjoiningbags 154.

Once again examining FIG. 2a , once the sets of closely spaced parallelseals 142 and perforation lines 144 are formed, the bag converter 140can fold the collapsed tube 110 one or more times, with each foldextending along the length of the collapsed tube 110 and parallel to themachine direction. In at least one particular embodiment, the collapsedtube 110 can be folded twice such that a width of the folded collapsedtube 110 a is one-fourth the width of the un-folded collapsed tube 110.Once folded, a first folded edge 112 a and second folded edge 114 a canbe defined in opposing edges of each bag 154.

Once the collapsed tube 110 is folded, it can proceed into a wave-cutter150. The wave-cutter 150, which may also be referred to as awave-cutting operation, creates wave-cuts 152. Wave-cuts 152 arewave-shaped perforations, extending across the width of the foldedcollapsed tube 110 a. The wave-cuts 152 can perforate the foldedcollapsed tube 110 a in the shape of a one-half sine wave extendingacross the width of the folded collapsed tube 110 a. In one particularembodiment, the peak-to-peak amplitude of the sine wave can beapproximately 5 inches but may vary considerably. Due to the collapsedtube 110 a being folded twice when each wave-cut 152 is made, whenun-folded each wave-cut can have, in general, a shape of two full sinewaves extending across the width of the collapsed tube 110.

The location of the wave-cut 152 in relation to the perforation line 144can be controlled by a timing operation 160. The timing operation 160can detect the location of each perforation line 144. The timingoperation 160 can rely upon a laser beam, infrared light, a sparkgenerator, or another form of an electromagnetic signal to detect eachperforation line 144. The detected location of each perforation line144, along with the fixed position of the timing operation 160 and thecollapsed tube 110 traveling at a steady state, can be used to time theincremental stretching operation 120 and wave-cutting operation 150 sothat each wave-cut 152 and incrementally stretched section 116 areplaced at predetermined locations. The timing operation 160 may be astandalone operation or may be integrated into the bag converter 150.

In at least one preferred embodiment, each wave-cut 152 can be centeredby the wave-cutter 150 about a height of an incrementally stretchedsection 116, in relation to the machine direction. Thus, a distance froma bottom of a wave-cut 152 to a lower boundary of an incrementallystretched section 116, the lower boundary separating an incrementallystretched section 116 from an un-stretched section 118, can be equal toa distance from a top of the wave-cut 152 to an upper boundary of theincrementally stretched section 116, the upper boundary opposite fromthe lower boundary. Each centered wave-cut 152 and incrementallystretched section 116 can be equidistant from adjacent perforation lines144. In this preferred embodiment, once the collapsed tube 110 isseparated at wave-cuts 152 and perforation lines 144 to form bags 154 a,an approximate one-half length of an incrementally stretched section 116is defined on each bag 154 a (in relation to a mid-point or average ofthe waveform of the wave-cut 152).

In a particular example of this embodiment, the perforation lines 144can be 100 inches away from each other. Each incrementally stretchedsection 116 and wave-cut 152 can also be separated from adjacentincrementally stretched sections 116 and wave-cuts 152 by 100 inches.Since the sections 116 and wave-cuts 152 are aligned or centered, amid-point of each section 116 and wave-cut 152 is located 50 inches awayfrom adjacent perforation lines 144.

Once the collapsed tube is folded and the wave-cuts 152 are placed, thefolded collapsed tube 110 a may be separated at the perforation lines144 and wave-cuts 152 into individual bags 154 with each bag having aheight of approximately 50 inches. Each bag 154 may then be overlappedwith an adjoining bag and rolled into a roll of bags as is known in theart.

Shown in FIG. 2b is alternative embodiment to the embodiment illustratedin FIG. 2a . The bag conversion process shown in FIG. 2b is similar tothe processes described for FIG. 2a except for the length and relativelocation of each incrementally stretched section. The incrementalstretching operation 220 of FIG. 2b is configured to stretch a greaterlength of collapsed tube 110 relative to the incrementally stretchedsection 116 of FIG. 2a , resulting in incrementally stretched sections216 and un-stretched sections 218. After being incrementally stretched,bag converter 240 can form sets of closely spaced parallel seals 242centered about a height of an un-stretched section 218 and perforationlines 244 centered within each set of closely spaced seals 242.

Further shown in FIG. 2b is wave-cutter 250 configured to place eachwave-cut 252 centered about a height of another un-stretched section 218resulting in individual bags 254 with a top open edge defined bywave-cut 252 and bottom seal 244. An incrementally stretched section 216is located in a central body and a first un-stretched section is locatedbelow the stretched body and a second un-stretched section is locatedabove the stretched body. Other details of the bag conversion processesof FIG. 2b are not explained further since it is duplicative with theprocesses as explained above for FIG. 2 a.

As one skilled in the may ascertain, the length of each incrementallystretched section 216 is greater than the incrementally stretchedsection 116 of FIG. 2a . For instance, rather than a stretched length of15 inches as described for FIG. 2a , the incremental stretching process220 may be configured to stretch the collapsed tube 210 approximately 30inches when configured for manufacturing bags with a total height of 50inches. This height could vary, however, depending upon the size of bagbeing manufactured and the desired length of the stretched body of thebag. The stretched body of the bag may centered between the bottom andtop of the bag or it may be offset to a degree towards the bottom or topof the bag. For similar sized bags as described for FIG. 2a , the otherdimensions discussed above would remain unchanged. However, the size ofthe rollers necessary for the incremental stretching operation discussedabove would change proportionally to accomplish the increased length ofthe incrementally stretched section.

FIGS. 5 and 6 show in detail the structure of the trash bags 154 thatmay be formed from the above-described processes of FIGS. 1, 2, and 3a-4 b. FIG. 5 shows that once adjacent perforation lines 144 areseparated, a matching pair of interconnected trash bags 154 are defined.A boundary of each trash bag is defined by one of the wave-cuts 152. Anincrementally stretched section 116 is shown located on the twoadjoining bags 154. Further shown is first edge 112 and second edge 114of the collapsed tube 110 defining two opposing sides of the twoadjoining bags 154. Two opposing perforation lines 144 are showndefining a bottom of each adjoining bag 154. Once the perforatedwave-cut 152 is separated, two separate trash bags result. One of theresultant trash bags 154 a is shown in FIG. 6.

As shown in FIG. 6, each wave-cut trash bag 154 a can comprise a frontpanel and a rear panel formed from opposing sides of the collapsed tube110. The trash bag 154 a can have a first side edge 112 b defined by thefirst edge 112 of the collapse tube 110 and a second side edge 114 bdefined by the second edge 114 of the collapsed tube 110. The trash bag154 can further have a bottom seal 142 a defined by one seal of theclosely spaced sets of seals 142. A bag bottom 144 a can be defined byone of the perforation lines 144. The bag top 152 a can be defined byone of the wave-cuts 152. The bag top 152 a can have a wave-cut profile.The bag top 152 a can be defined on both the front panel and back panelof the bag 154 a and the bag top 152 a can define a bag opening.

As shown in FIGS. 2, 5 and 6, an incrementally stretched portion 158 ofthe trash bag 154 a can be comprised of an incrementally stretchedsection 116 of the collapsed tube 110. The incrementally stretchedportion 158 can be a fractional length of one of the incrementallystretched sections 116. Within the incrementally stretched portion 158,a plurality of lobes 156 can be defined. The plurality of lobes 156 mayalso be referred to as tie-flaps. A wave-cut profile height H can bedefined as a vertical distance from a top of the wave-cut profile to abottom of the wave-cut profile, the wave-cut profile height H equal toan peak-to-peak amplitude of the wave shape of the wave-cut profile. Theincrementally stretched portion 158 can extend from the bag top 152 a toat least the bottom of the wave-cut profile. However, at least in oneembodiment, the incrementally stretched portion 158 can extend below thebottom of the wave-cut profile up to one-half the wave-cut profileheight H. In an alternative embodiment, the incrementally stretchedportion 158 can extend below the bottom of the wave-cut profile at leasta distance equal to the wave-cut profile height H. The incrementallystretched portion 158 can define a plurality of ribs extending from thefirst side edge 112 b to the second side edge 114 b of the bag 154 a.The plurality of ribs can generally be parallel to each other andtransverse to both the first side edge 112 b and second side edge 114 b.

In one particular example of the wave-cut trash bag 154 a, a height ofthe bag from the bag bottom 144 a to the upper extent of the bag top 152a may be 50 inches. A width of the bag from the first side edge 112 b tothe second side edge 114 b may be approximately 33 inches. The wave-cutprofile height H may be 5 inches with the incrementally stretchedportion 158 extending 2.5 inches below the bottom of the wave-cutprofile. Thus, the incrementally stretched portion 158 may have a heightof approximately 7.5 inches, resulting in the remaining 42.5 inches ofbag height un-stretched. The incrementally stretched portion 158 may bestretched approximately 15%. Thus, if the film of the collapsed tube isformed with a thickness of 3 mil, the incrementally stretched portion158 may have an average thickness of approximately 2.5 mil with theremaining portions of the bag having a thickness of 3 mil.

Shown in FIGS. 7 and 8 is an alternative embodiment of the inventionformed by the processes detailed by FIG. 2b as described above. Ratherthan each incrementally stretched section 116 aligned with one of thewave-cuts 152, each incrementally stretched section 116 can be offsetfrom each wave-cut 152, as explained for FIG. 2b above. In thisembodiment, each incrementally stretched section 116 is between adjacentperforation lines 140 and wave-cuts 152 so that a bag body 160 of eachresultant bag 154 is incrementally stretched. The bag body 160 can belocated between the lower extent of the bag top 152 a and the bag bottom144 a.

Further shown in FIG. 8 are incrementally stretched transition zones 160a and 160 b. It has been determined that when a polymeric web undergoesan incremental stretching operation as discussed above, the film of theweb undergoes a transition from un-stretched film to fully incrementallystretched film. This transition is represented by the transitions zones160 a and 160 b shown in FIG. 8. The structure of these transition zonesis further detailed below in the discussion of FIG. 11.

In one particular example of the embodiment shown in FIGS. 7 and 8, theintermeshing rollers 122 a, 122 b can engage the collapsed tube 110approximately 2.5 inches away from each side of each perforation line142. Each incrementally stretched section 116 can be approximately 40inches long, which results in a length of approximately 7.5 inches ofun-stretched film from the upper extent of the bag top 152 a to a top ofthe incrementally stretched bag body 160 for a bag having a total lengthof 50 inches. The bag body 160 can be stretched approximately 17 percentso that an initial film thickness of 3 mil is stretched to approximately2.5 mil within the bag body 160. This embodiment allows less film, andhence less polymeric material, to be used than an otherwise similarun-stretched bag.

It is foreseeable, however, that the bag may disclosed in FIGS. 7 and 8be shorter in length, such as 33 inches in length, since it iscontemplated that bag 154 a with an incrementally stretched body wouldbe desirable for thinner wave-cut bags between 1-2 mils than the heavier3 mil thick bags. Nonetheless, for bags in shorter lengths, such as 33inches, it is contemplated that the other above discussed dimensionswould be proportional to the dimensions discussed above for a bag havinga length of 50 inches. It is further contemplated that a desirablethickness of bag 154 a, as illustrated by FIG. 8, with a length of 33inches may be approximately 1.3 mils. In at least one embodiment, it maybe desirable to stretch central body of such a bag approximately 20%that results in the gauge by weight of the bag body being approximatelyone mils.

The embodiment shown in FIGS. 7 and 8 may also be implemented on awave-cut trash bag having typical dimensions of a kitchen trash bagwith. The bag body 160 can be stretched approximately 16 percent so thatan initial film thickness of 0.7 mil is stretched to approximately 0.6mil within the bag body 160.

FIG. 9 illustrates yet another embodiment of the incremental stretchingoperation. Shown in FIG. 9 is a top planar view of an alternateembodiment of the outer surface of upper intermeshing roller 122 a. Theclosely spaced parallel lines of FIG. 9 represent edges of eachprotruding ridge 126 a. Although not to the same extend as previousillustrations, the spacing between adjacent ridges is exaggerated forease of illustration. For reference, shown in dashed lines is theoutline of the intended corresponding placement of a wave-cut 152.Within the plurality of protruding ridges 126 a is shown a plurality ofridge voids 132. Each ridge void 132 is a location from which a lengthof protruding ridges has been removed from the intermeshing roller 122a. Each ridge void 132 defines a location where the intermeshing roller122 a will fail to stretch the collapsed tube 110 within eachincrementally stretched section 116. The ridge voids 132 are locatedabout the intermeshing roller 122 a such that an upper region of eachlobe 156 of each bag 154 is left un-stretched.

FIG. 10 illustrates the structure of bag 154 a formed by the alternateembodiment of the incremental stretching operation as illustrated byFIG. 9. As a result of the plurality of ridge voids 132, defined in anupper region of each lobe 156 is an un-stretched tip 132 a that isdevoid of any ribs that otherwise would have been formed by theincremental stretching operation. As shown in FIG. 10, a plurality ofun-stretched tips 132 is defined on the bag 154. In a likewise manner,the incrementally stretched portion 158 of the bag does not extend tothe upper extent of the bag top 152 a. The remaining features of bag 154a remain unchanged from the embodiment illustrated in FIGS. 5 and 6. Theun-stretched tips 132 a may further improve the ease of tying thewave-cut trash bag versus the previously described embodiments.

Shown in FIG. 11 is a side view of a partial length of film, with thethickness of the film exaggerated for clarity, subjected to anintermittent incremental stretching process as discussed above. Prior toentering an incremental stretching operation, such as operation 120shown in FIG. 2a , the height, or thickness of the web 170, e.g.collapsed tube 110, is initially a first height H1 as shown in FIG. 11.The first height H1 is approximately equivalent to the gauge of the web.The incremental stretching operation forms thick ribs 172 and thin ribs174 into the web 170. When the stretching operation initially engagesthe web 170, an initial height of the cross section of the web is asecond height H2, a first transition height, since the stretchingoperation requires a certain amount of web length to fully engage theweb 170. Multiple additional thin ribs of decreasing transition height(not shown) can be formed as the incremental stretching operationfurther engages the web 170. Once the stretching operation reaches asteady state operation, the height of each thin rib 174 decreases to aconstant third height H3 that is maintained until the incrementalstretching operation begins to disengage the web 170. The length of theweb encompassing the thin ribs having heights between H1 and H3 can bedefined as a first transition zone.

Although not shown in FIG. 11, when the incremental stretching operationbegins to disengage the web 170, the transition reverses with a certainamount of thin ribs 174 having varying increasing heights, transitioningfrom the third height H3 until reaching the first height H1 once theincremental stretching operation fully disengages web 170. The length ofweb that encompasses the thin ribs with increasing heights between H3and H1 can be defined as a second transition zone. This cycle oftransition zones repeats when the incremental stretching operation isengaged once again for the next section of incrementally stretched film.

Shown in FIGS. 12-16 is a further embodiment of the present invention.Rather than incrementally stretching the bags, the process of FIGS.12-16 intermittently embosses a pattern onto the collapsed tube 110. Theembossed pattern allows the collapsed tube 110 to expand in thecross-direction to absorb shock in the cross-direction. Certain featuresof collapsed tube 110 remain unchanged from the previously discussedembodiment. These features share the same reference numbers and thedisclosure above may be referenced for explanation of these sharedfeatures.

The embossing pattern utilized on the collapsed tube as shown in FIGS.12-16 allows bags manufactured from the disclosed process to expand inthe cross-direction, in the width direction of the bags, from a firstside edge to a second side edge of the bag, to increase the capacity ofthe bags when filled with debris. The embossing pattern further preventsthe propagation of tears due to the tortuous path defined by theembossed pattern since a straight line cannot pass through more than oneembossed region without intersecting an adjacent embossed region.

Shown in FIG. 14 is a detailed schematic view of a certain embodiment ofthe embossed pattern as illustrated generally in FIGS. 12 and 13. Theembossed pattern 600 has a plurality of embossed regions 610, eachembossed region 610 having a generally hexagonal shape with eachembossed region 610 separated by a continuous unembossed arrangement620. One of the hexagonal shapes is indicated by dashed lines A in FIG.14. The dashed lines of A are shown for reference only and form nostructure of the disclosed invention. Each embossed region 610 is shownas defined by nine parallel and adjacent linear embosses 630. The twoopposing horizontally extending sides of each embossed region 610 isdefined by three middle adjacent parallel linear embosses 630 with equallength; each horizontal side of the hexagon formed by adjacent ends ofthe three linear embosses 630. Each of the other four diagonal sides ofthe hexagon can be defined by an endpoint of an outer emboss of thethree middle adjacent linear embosses 630 and adjacent end points ofthree other outer adjacent linear embosses 630. Each of the three otheradjacent linear embosses 630 can decrease in length the same amount asthe adjacent linear emboss 630.

The hexagonal shaped embossed regions 610 of FIG. 14 can be orientedsuch that opposing vertices of each hexagon are at a left and right sideof each hexagon is illustrated in FIG. 14. Adjacent to the vertices canbe two short opposing, linear embosses 630 at each end of each embossedregion 610. These opposing vertices encourage each embossed region tofold-in when the linear embosses unfold in the horizontal direction.Hence, a film with the embossed pattern 600 of FIG. 14 expands in thehorizontal direction but not in vertical direction. This expansion ismuch greater and at a much lower force than would be required to stretchthe unembossed film.

With the embossed pattern applied to the collapsed tube 110 with thelinear embosses 630 extending in the machine direction and the opposingvertices aligned in the cross-direction, the embossed pattern 600 asshown in FIGS. 12, 13, 15 a, and 15 b allows the polymeric film of thecollapsed tube 110 to expand in the cross-direction of the collapsedtube 110. Due to the hexagonal shape of the embossed regions 610, thedepicted embodiment of the embossed pattern 600 provides features toprevent tear propagation since a tear propagating in the cross directionwill be interrupted by an embossed region 610.

FIG. 14 depicts the unembossed arrangement 620 having a plurality offirst segments 620 a, a plurality of second segments 620 b, and aplurality of third segments 620 c. Each embossed region 610 is boundedby two first segments 620 a, two second segments 620 b, and two thirdsegments 620 c. Each first segment 620 a extends in a first directionthat is generally horizontal. Each second segment 620 b extends in asecond direction that is oblique to the first direction. Each thirdsegment 620 c extends in a third direction that is oblique to both thefirst direction and the second direction. The first, second, and thirddirections are all distinct from each other. As shown in FIG. 14, eachof the segments 620 a, 620 b, or 620 c are interrupted by an adjacentembossed region 610, failing to extend past more than one embossedregion 610.

As further shown in FIG. 14, the first segments 620 a intersect both thesecond segments 620 b and third segments 620 c. Furthermore, a firstsegment 620 a, a second segment 620 b, and a third segment 620 c allintersect each other adjacent to both the upper and lower vertices ofeach embossed region 610. In a particular embodiment of the embossedpattern 600, the angle formed by each intersection by a first segment620 a with a second segment 620 b or third segment 620 c can beapproximately 54 degrees or the supplementary angle of 126 degrees. Inthe same embodiment, the angle formed by each intersection of a secondsegment 620 b with a third segment 620 c can be approximately 108degrees.

The preferred actual size and spacing of the embossed pattern 600 issubstantially exaggerated for ease of illustration in the figures.However, in one preferred embodiment, the spacing of the ridges can beabout 20 ridges per inch about the circumference of the first roller 322a so that each embossed region 610 is about 0.45 0.5 inch in length.

Now returning to the bag formation process of FIGS. 12 and 13, thecollapsed tube 110 can feed directly into embossing operation 320 oncethe film exits the nip rollers 108 of the extrusion operation 102, aspreviously discussed in regards to FIGS. 1 and 2 a. Thus, the embossingcan be performed as an in-line process, synchronously, with the blownfilm extrusion. As shown in the figures, the embossing operation 320 canbe configured to only intermittently emboss the collapsed tube 110,leading to embossed partial lengths of the collapsed tube 110. Theseembossed partial lengths of the collapsed tube can define a plurality ofembossed sections 316 and unembossed sections 318 in the collapsed tube110 as shown in FIGS. 12 and 13.

As best shown in FIGS. 15a and 15b , the embossing operation 320 caninclude a pair of intermeshing rollers 322 a, 322 b. The diameter andlength of the first intermeshing roller 322 a and the secondintermeshing roller 322 b can be equal in at least certain embodiments.As further shown in FIG. 15a , the collapsed tube 110 can enter nip 124defined by the pair of intermeshing rollers 322 a, 322 b. The rotationalaxes 328 a, 328 b of each roller 322 a, 322 b can be parallel to eachother and transverse to the machine direction (MD) of the collapsed tube110 as shown in the figures.

As illustrated by FIGS. 15a and 15b , the first intermeshing roller 322a can have a plurality of concentric ring-shaped ridges 326 andcorresponding grooves extending about the circumference of the firstroller 322 a. The ridges 326 can be evenly dispersed about the length ofthe roller 322 a. As explained further below, the second roller 322 bcan have an embossing pattern defined about its surface. The concentricridges 326 of the first roller are constructed to intermesh with theembossing pattern of the second roller 322 b. With the embossing patterndefined on the second roller 322 b, as the collapsed tube 110 enters thenip of the intermeshing rollers 322 a, 322 b, the film of the collapsedtube 110 is embossed with the embossing pattern 600.

Shown in FIG. 16 is a detailed planar or flattened view of a section ofthe circumferential surface of the second intermeshing roller 322 b. Theorientation of the embossing pattern 500 is oriented approximately 90degrees from its orientation as illustrated in FIGS. 15a and 15b forease of illustration. As shown in FIG. 16, the embossing pattern 500 canhave a plurality of embossment regions 510. The hexagonal shape of oneof the embossment regions 510 is indicated by dashed lines B in FIG. 16,which is shown for reference only and forms no structure of thedisclosed invention. As further shown in FIG. 16, each embossment region510 can comprise a plurality of embossment ridges 512. Each of theembossment ridges can be parallel to each other and generally spacedevenly from each other.

As further shown in FIG. 16, each of the embossment regions can bebounded by a continuous embossment boundary 520. The embossment boundarycan be substantially flat in relation to the embossment ridges 512 anddevoid of any embossment ridges. The embossment boundary 520 cancomprise first segments 520 a, second segments 520 b, and third segments520 c. As shown in FIG. 16, each of the three segments can extend in adifferent direction from each other. As should be apparent to one ofordinary skill in the art, the surface of the section illustrated inFIG. 16 necessarily follows the curvature of the surface of secondroller 322 b but is shown without the curvature (planar) for ease ofillustration. The features of the embossing pattern 500 correspond withthe emboss pattern 600 of FIG. 14. FIG. 16 is provided to illustrate thepattern on intermeshing roller 322 b which results in forming the embosspattern 600 on collapsed tube 110 due to the embossing operation 320.

Now returning to FIGS. 15a and 15b , the embossment ridges 512 (notshown) of the second intermeshing roller 322 b, which follow thecurvature of roller 322 b, are offset from the concentric ridges 326 ofthe first roller 322 a so that the ridges of the two rollers intermesh.As illustrated in FIG. 15a , once the collapsed tube 110 passes throughthe two intermeshed rollers 322 a and 322 b, the embossed pattern 600,as illustrated by FIG. 14, is formed into the polymeric film of thecollapsed tube 110.

As best shown in FIGS. 12 and 13, the film of the collapsed tube 110 isembossed with the embossed pattern 600 intermittently, due tointermittent engagement of the intermeshing rollers 322 a and 322 b, asthe collapsed tube 110 travels in the machine direction. Thisintermittent embossing results in a pattern of embossed and unembossedsections 316 and 318 on the collapsed tube 110. As illustrated in FIGS.15a and 15b , the intermittent engagement of the collapsed tube 110 canbe accomplished by the axes 328 a and 328 b of the pair of intermeshingrollers 322 a, 322 b moving away from each other a certain distance tocreate a gap G between the surface of the two rollers. This gap G allowsthe collapsed tube 110 to move past the embossing operation 320 withoutbeing embossed by the intermeshing rollers 322 a, 322 b. The gap G, asshown in FIG. 15b , must be large enough to allow the collapsed tube 110to pass through the nip 124 without interference from the intermeshingrollers 322 a, 322 b.

Examining the FIGS. 15a and 15b in detail illustrates the intermittentengagement and disengagement of the intermeshing rollers 322 a, 322 bthat define the embossed and unembossed sections 316 and 318 in thecollapsed tube 110. FIG. 15a shows the two intermeshing rollers 322 a,322 b intermeshed with each other, with no gap, engaging the film of thecollapsed tube 110 and forming an embossed section 316 as the collapsedtube 110 travels in the machine direction. FIG. 15b shows the twointermeshing rollers 322 a, 322 b with the gap G between the rollers,not engaged, and hence no embossing taking place to define an unembossedsection 318 on the film of the collapsed tube 110 as the tube continuesto travel in the machine direction past the two intermeshing rollers 322a, 322 b.

In an alternative embodiment, the above-described embossing operation320 can be performed on a single layer web of polymeric film. Forinstance, the collapsed tube 110 may be slit along the first edge 112 sothat the tube is open along the first edge 112. The collapsed tube maythen be spread out so that the two opposing layers of the collapsed tube110 lie in the same plane adjacent to each other. The single layer webmay then be intermittently embossed as described above. Once theembossing is complete, the web may be folded so that the two layers ofthe collapsed tube 110 once again oppose each other. The two layers offilm adjacent to the first edge 112 may then be sealed together so thatthe collapsed tube 110 may still be used to form wave-cut trash bags.Performing the embossing on one layer of film may prevent undesiredbinding of the two layers of film.

In another alternative embodiment, rather than the embossing operation320 performed in-line and synchronously, as described above, with theblown film extrusion 102, the embossing 320 can be performed off-linefrom the blown film extrusion. For instance, once the polymeric bubble104 is collapsed by the nip rollers 108, the collapsed tube 110 can berolled onto a master roll. The master roll can then be placed at a leadend of the embossing operation 110 and the collapsed tube can beunrolled from the master roll. The collapsed tube 110 can then be fedinto the embossing operation 320.

Returning now to FIGS. 12 and 13, it may be desirable to provide niprollers on both sides of the embossing operation 320 to control tensionin the collapsed tube as it enters and exits the intermeshing rollers322 a and 322 b of the embossing operation 320. FIGS. 12 and 13 shows apair of pre-embossing rollers 380 controlling tension in the collapsedtube prior to the film's entry into the nip of the intermeshing rollersof the embossing operation 320, or upstream to the embossing operation320. The figures further show a pair of post-embossing rollers 382controlling tension in the collapsed tube 110 upon exiting theintermeshing rollers of the embossing operation 320, or downstream fromthe embossing operation 320. Both the pre and post embossing rollers 380and 382 are typical nip rollers as known in the art. The rotationalspeed of the pre and post embossing rollers 380 and 382 may becontrolled independently from each other and from the intermeshingrollers 322 a and 322 b so that the tension in the collapsed tube 110may be adequately controlled to aid in the desired engagement of theintermeshing rollers 322 a and 322 b into the polymeric film of thecollapsed tube 110.

As further shown by FIGS. 12 and 13, once the embossing is completed byembossing operation 320, the collapsed tube 110 can enter a bagconverter 140. The bag converter 140 can form sets of closely spaced,parallel seals 142. The sets of closely spaced parallel seals 142 canextend transverse to the machine direction and across the entire widthof the collapsed tube 110. As shown in FIGS. 17 and 18, one seal of eachset 142 can define a bottom seal 142 a for each bag 354 a. As shown inFIG. 13, between each set of the closely spaced parallel seals 142, thebag converter 140 can form perforation lines 144. The perforation lines144 can extend transversely to the machine direction, the crossdirection, and across the entire width of the collapsed tube 110. Eachperforation line 144 can define the bag bottom 144 a (shown in FIG. 17)and separation point of adjoining bags 354.

Once again examining FIG. 13, once the sets of closely spaced parallelseals 142 and perforation lines 144 are formed, the bag converter 140can fold the collapsed tube 110 one or more times, with each foldextending along the length of the collapsed tube 110 and parallel to themachine direction. In at least one particular embodiment, the collapsedtube 110 can be folded twice such that a width of the folded collapsedtube 110 a is one-fourth the width of the un-folded collapsed tube 110.Once folded, a first folded edge 112 a and second folded edge 114 a canbe defined in opposing edges of each bag 354.

Once the collapsed tube 110 is folded, it can proceed into a wave-cutter150. The wave-cutter 150, which may also be referred to as awave-cutting operation, creates wave-cuts 152. Wave-cuts 152 arewave-shaped perforations, extending across the width of the foldedcollapsed tube 110 a. The wave-cuts 152 can perforate the foldedcollapsed tube 110 a in the shape of a one-half sine wave extendingacross the width of the folded collapsed tube 110 a. In one particularembodiment, the peak-to-peak amplitude of the sine wave can beapproximately 5 inches but may vary considerably. Due to the collapsedtube 110 a being folded twice when each wave-cut 152 is made, whenun-folded each wave-cut can have, in general, a shape of two full sinewaves extending across the width of the collapsed tube 110.

Once the collapsed tube is folded and the wave-cuts 152 are placed, thefolded collapsed tube 110 a may be separated at the perforation lines144 and wave-cuts 152 into individual bags 354 with each bag having aheight of approximately 50 inches in certain embodiments. Each bag 354may then be overlapped with an adjoining bag and rolled into a roll ofbags as is known in the art.

The location of the wave-cut 152 in relation to the perforation line 144can be controlled by a timing operation 160. The timing operation 160can detect the location of each perforation line 144. The timingoperation 160 can rely upon a laser beam, infrared light, a sparkgenerator, or another form of an electromagnetic signal to detect eachperforation line 144. The detected location of each perforation line144, along with the fixed position of the timing operation 160 and thecollapsed tube 110 traveling at a steady state, can be used to time theembossing operation 320 and wave-cutting operation 150 so that eachwave-cut 152 and embossed section 316 are placed at predeterminedlocations. The timing operation 160 may be a standalone operation or maybe integrated into the bag converter 150. In an alternative embodiment,the timing of the embossing operation 320 may utilize the timing of theperforation operation itself rather than detection of the perforationline 144 to synchronize the engagement of the embossing operation 320while the engagement of the wave-cutting operation may be based on anindependent detection of the perforation line 144.

As shown in FIGS. 12 and 13, for each perforation line 144 placed incollapsed tube 110 two embossed sections 316 can be placed into thecollapsed tube 110. Thus, the timing operation 160 may be configured toengage the embossing operation 320 two times for each perforation line144 formed or detected in the collapsed tube 110.

Now turning to FIGS. 17 and 18, the structure of the trash bags 354formed from the above-described processes of FIGS. 12-16 is shown. FIG.17 illustrates that once adjacent perforation lines 144 are separated, amatching pair of interconnected trash bags 354 are defined. A boundaryof each trash bag is defined by one of the wave-cuts 152. An embossedsection 316 is shown located on each of the two adjoining bags 354.Further shown is first edge 112 and second edge 114 of the collapsedtube 110 defining two opposing sides of the two adjoining bags 354. Twoopposing perforation lines 144 are shown defining a bottom of eachadjoining bag 354. Once the perforated wave-cut 152 is separated, twoseparate trash bags result. One of the resultant trash bags 354 a isshown in FIG. 18. As may be apparent to one having ordinary skill theart, that due to folding operation 140 as shown in FIGS. 12 and 13, thepair of bags 354 may be folded once wave-cut 152 is applied and formedin bags 354 but bags are shown unfolded for ease of illustration.

Returning now to FIG. 18, an individual bag 354 a is shown. Eachwave-cut trash bag 354 a comprises a front panel and a rear panel, orfirst and second panels, formed from opposing sides of the collapsedtube 110. However, the front and rear panels are mirror images of eachother and hence only a front panel is illustrated in FIG. 18. FIG. 18shows trash bag 354 a with a first side edge 112 b defined by the firstedge 112 of the collapse tube 110 and a second side edge 114 b definedby the second edge 114 of the collapsed tube 110. The trash bag 354 isfurther shown with a bottom seal 142 a defined by one seal of theclosely spaced sets of seals 142. A bag bottom 144 a or bottom edge isshown as defined by one of the perforation lines 144. The bag top 152 acan be defined by one of the wave-cuts 152. The bag top 152 a has awave-cut profile due to the wave-cut 152. The bag top 152 a is definedon both the front panel and back panel of the bag 354 a with the bag top152 a defining a bag opening.

As illustrated by FIGS. 13, 17 and 18, an embossed section 358 of thetrash bag 354 a can be comprised of an entire embossed section 316 ofthe collapsed tube 110. A plurality of lobes 156 can be defined by thewave-cut profile 152 a as shown in FIG. 18. The plurality of lobes 156may also be referred to as tie-flaps. The wave-cut profile height H isshown as the vertical distance from a top of the wave-cut profile to abottom of the wave-cut profile, the wave-cut profile height H equal to apeak-to-peak amplitude of the wave shape of the wave-cut profile.Furthermore, as best illustrated by FIG. 18, wave-shaped profile 152 acomprises one or more crests 156 a, or peaks of the wave shape, andtroughs 156 b, or valleys, of the wave shape of the wave-shaped profile.

Further shown in 18, embossed section 358 is offset from wave-cut 152 a.Embossed section 358 is shown between perforation line 144 a andwave-cut 152 a so that the embossed section 358 is located in the bodyof bag 354 a. Embossed section 358 is shown extending from the firstside edge 112 b to the second side edge 114 b and from a lowerembossment boundary 372 to an upper embossment boundary 370. Embossedsection 358 is further shown below the troughs 156 b of the wave-shapedprofiled 156. The bag body can be located between the lower extent ofthe bag top 152 a and the bag bottom 144 a.

FIG. 18 further illustrates the upper embossment boundary 372 below thetroughs 156 b of the wave-shaped profile 152 a and the lower embossmentboundary 374 above the bottom seal 142 a. Both upper and lowerboundaries 370 and 372 are shown extending from the first side edge 112b to the second side edge 114 b and generally parallel to the bottomseal 142 a and hence generally perpendicular to the two side edges 112 band 114 b.

Further shown in FIG. 18 above upper embossment boundary 370 and belowlower embossment boundary 372 are upper and lower unembossed sections362 and 364. Unembossed sections 362 and 364 are substantial flat anddevoid of embossments since the embossing operation 320 has not beenapplied to these areas of the polymeric film of the collapsed tube 110.The unembossed sections 362 and 364 are generally flat in comparison tothe embossed section 358 but can be expected to have a certain amount ofsurface roughness and unevenness due to typical surface variations of apolymeric film produced by a blown film extrusion process. Bothunembossed sections 362 and 364 are shown extending from the first side112 b to the second side edge 114 b of bag 354 a. Upper unembossedsection 364 is further shown extending from the upper embossmentboundary 370 to the crests 156 b of the wave-cut profile and lowerunembossed section 362 is shown extending from the lower embossmentboundary 372 to the bag bottom or bottom edge 144 a.

Further shown in FIG. 18 are embossed transition zones 358 a and 358 b.It has been determined that when a polymeric film undergoes an embossingoperation as discussed above, the film undergoes a gradual transitionfrom an un-embossed section to a fully embossed section of film. Thistransition is represented by the transitions zones 358 a and 358 b shownin FIG. 18. Due to the gradual engagement of the intermeshing rollers322 a and 322 b of the collapsed tube 110, the linear embosses adjacentto upper and lower embossment boundaries 370 and 372 taper with adecreasing height as the linear embosses extend from within the embossedsection 358 towards the unembossed sections 362 and 364 above and belowthe embossed section 358.

In a particular example of the embodiment of FIG. 17 of the pair of bags354, the perforation lines 144 can be 113 inches away from each other.Each wave-cut 152 can also be separated from adjacent wave-cuts 152 by113 inches. The peak-to-peak amplitude of the wave-cut 152 a, H, can beabout 5 inches which is shared between the two bags. Hence, the heightof an individual bag 354 a can be about 54 inches. The upper embossmentboundary 370 can be about 2 inches below the troughs 156 b of thewave-cut 152 a and the lower embossment boundary 372 can be about 2inches above the bottom perforation or edge of bag 144 a. Thesedimension results in the embossed section 358 having a height of about45 inches. It is further contemplated that the embodiment shown in FIGS.17 and 18 may also be implemented on a wave-cut trash bag havingdimensions of a typical kitchen trash bag.

As previously noted, the specific embodiments depicted herein are notintended to limit the scope of the present invention. Indeed, it iscontemplated that any number of different embodiments may be utilizedwithout diverging from the spirit of the invention. Therefore, theappended claims are intended to more fully encompass the full scope ofthe present invention.

What is claimed is:
 1. A method of forming a bag of polymeric film, themethod comprising: forming a collapsed tube of polymeric film, thecollapsed tube having a machine direction, a pair of intermeshingrollers intermittently engaging and disengaging the collapsed tube toform a plurality of embossed sections and a plurality of unembossedsections, each embossed section comprising a plurality of embossedregions, each embossed region separated from adjacent embossed regionsby an unembossed arrangement, and forming the collapsed tube into aplurality of bags, each bag comprising at least a fraction of one of theplurality of embossed sections.
 2. The method of claim 1, the methodfurther comprising: each of the plurality of embossed sections extendingacross the entire width of the collapsed tube.
 3. The method of claim 1,the forming of the collapsed tube into a plurality of bags furthercomprising: forming sets of closely spaced, parallel seals extendingtransversely across a width of the collapsed tube at equally spacedintervals, forming perforation lines extending transversely across thewidth of the collapsed tube between each set of parallel seals, a uniqueperforation line between one set of the sets of parallel seals,generating a timing signal for the unique perforation line, the timingsignal based on a location of the unique perforation line, a location ofone of the plurality of the embossed sections determined from the timingsignal, forming a plurality of wave-shaped perforations extending acrossthe width of the collapsed tube, a location of one of the plurality ofthe wave-shaped perforations determined from the location of the uniqueperforation line.
 4. The method of claim 3, the method furthercomprising: the timing signal triggering the intermeshing rollers toengage and disengage the collapsed tube twice to form two embossedsections for each timing signal.
 5. The method of claim 1, the methodfurther comprising: the pair of intermeshing rollers rotating about anaxis of rotation in an opposite direction from each other, the pair ofintermeshing rollers comprising a first roller and a second roller, thefirst roller including a plurality of grooves perpendicular to the axisof the first roller, the plurality of grooves on the first rollerintermeshing an embossing pattern on the second roller, the axis of eachroller parallel to each other, each intermeshing roller rotating towardseach other in the machine direction so that the bubble is drawn throughthe pair of intermeshing rollers, and a pair of post-embossing rollersdownstream from the pair of intermeshing rollers that maintains tensionin the collapsed bubble.
 6. The method of claim 5, the method furthercomprising: a pair of pre-embossing rollers upstream from the pair ofintermeshing rollers that cooperates with the pair of post-embossingrollers to maintain tension in the collapsed bubble.
 7. The method ofclaim 5, the method further comprising: the embossing pattern comprisinga plurality of embossment regions defined in the second roller, eachembossment region comprising a set of embossment ridges.
 8. The methodof claim 7, the method further comprising: each set of embossment ridgescomprising linear ridges parallel to each other, each embossment regiondefined by a continuous embossment boundary, the embossment boundarygenerally flat, the embossment boundary comprising at least a pluralityof first segments and a plurality of second segments, the plurality offirst segments extending in a first direction and the plurality ofsecond segments extending in a second direction, and the first andsecond directions distinct from each other.
 9. The method of claim 8,the method further comprising: the embossment boundary furthercomprising a plurality of third segments extending in a third direction,the third direction distinct from the first and second directions. 10.The method of claim 8, the method further comprising: each embossmentregion comprising at least 8 embossment ridges.
 11. A bag formed from acollapsed tube of polymeric film, the bag comprising: a first panel anda second panel, the first panel and the second panel joined along afirst side edge, a second side edge, and a bottom edge, the first sideedge defined by a first edge of the collapsed tube and the second sideedge defined by a second edge of the collapsed tube, the first panelhaving a first top edge opposite the bottom edge and the second panelhaving a second top edge opposite the bottom edge, the first top edgeand second top edge defining an opening of the bag, a distal end of boththe first top edge and second top edge having a wave-shaped profile, thewave-shaped profile defining a plurality of lobes, and an embossedsection defined only below the plurality of lobes, the embossed sectioncomprising an embossed pattern of a plurality of embossed regions, eachembossed region separated from adjacent embossed regions by anunembossed arrangement, the embossed section extending between the firstside edge and the second side edge, wherein the embossed pattern isarranged such that the bag expands between the first and second sideedge when filled with debris.
 12. A bag formed from a collapsed tube ofpolymeric film, the bag comprising: a first panel and a second panel,the first panel and the second panel extending from a first side edge toa second side edge of the collapsed tube, the first panel and the secondpanel joined along the first side edge, the second side edge, and abottom seal proximate to a bottom edge, the bottom seal extending fromthe first side edge to the second side edge, the first and second panelseach having a top edge opposite the bottom edge defining an opening ofthe bag, each top edge having a wave-shaped profile, the wave-shapedprofile comprising a plurality of crests of troughs, an upper embossmentboundary defined below the plurality of troughs of the wave-shapedprofile, the upper embossment boundary extending from the first sideedge to the second side edge, a lower embossment boundary defined belowthe upper embossment boundary and above the bottom seal, the lowerembossment boundary extending from the first side edge to the secondside edge, an embossed section extending between the first side edge tothe second side edge and from the upper embossment boundary to the lowerembossment boundary, the embossed section comprising a plurality ofembossed regions of embossments, each embossed region separated fromadjacent embossed regions by an unembossed arrangement, a firstunembossed section extending from the upper embossment boundary to theplurality of crests and from the first side edge to the second sideedge, the first unembossed section having a generally flat surfacedevoid of embossments, and a second unembossed section extending fromthe lower embossment boundary to the bottom edge and from the first sideedge to the second side edge, the second unembossed section having agenerally flat surface devoid of embossments.
 13. The bag of claim 12further comprising: the continuous, unembossed arrangement comprising atleast a plurality of first segments and a plurality of second segments,the plurality of first segments extending in a first direction and theplurality of second segments extending in a second direction, and thefirst and second directions distinct from each other.
 14. The bag ofclaim 12 further comprising: the first and second embossment boundariesgenerally linear and parallel to the bottom seal.
 15. The bag of claim14 further comprising: a machine direction of the collapsed tubeextending in a direction generally perpendicular to the bottom seal. 16.The bag of claim 15 further comprising: the bottom seal generallyperpendicular to the first side edge and the second side edge.
 17. Thebag of claim 12 further comprising: each embossed region comprisinglinear ribs, each linear rib generally parallel to the first side edgeand the second side edge.
 18. The bag of claim 17 further comprising: afirst transition zone between the embossed section and the firstunembossed section.
 19. The bag of claim 18 further comprising: thefirst transition zone comprising a plurality of linear embossments, theplurality of linear embossments having tapering heights with a height ofthe linear embossments decreasing as the linear embossments extendtowards the first unembossed section.
 20. The bag of claim 16 furthercomprising: the embossed section formed from a pair of intermeshingrollers.